Landscapes of Northern Lombardy: from the glacial scenery of Upper Valtellina to the prealpine lacustrine environment of Lake Como

In the region between Valtellina and Lake Como in the Central Italian Alps, one can visit, in a relatively small area, some of the best examples of mountain geomorphological landscapes of Italy. Eight specific sites-showing peculiar glacial, periglacial, structural, gravity-induced and erosional landforms-have been selected to illustrate how different landscapes may originate from geomorphological modelling of different lithotypes in different morphogenetic systems. These eight sites are exemplary cases in which significant evidence of past and current climatic and structural conditions characterising this region is exhibited

Towards a map of the Upper Pleistocene loess of the Po Plain Loess Basin (Northern Italy)

Upper Pleistocene (MIS 4-2) loess sequences occur in most of continental Europe and in Northern Italy along the Po Plain Loess Basin. Loess is distributed along the flanks of the Po Plain and was deposited on glacial deposits, fluvial terraces, uplifted isolated hills, karst plateaus, slopes and basins of secondary valleys. Loess bodies are generally tiny and affected by pedogenesis, being locally slightly reworked by slope processes and bioturbation. Notwithstanding, loess in the Po Plain is an important archive of paleoenviron-mental record and its mapping provides new insights in paleoenvironmental and palaeoseismic reconstructions of Northern Italy

Glaciers and ice sheets: Current status and trends

About 10 % of the land surface on Earth is covered by glacier ice, with an estimated total volume equivalent to about 66 m of potential sea-level rise. Almost the totality (99 %) of this volume is locked in the polar ice sheets, while less than 1 % forms all the other mountain glaciers and ice caps. In the last three decades, the general retreat of the mountain glaciers and the accelerated flow and ice loss from several outlet glaciers draining the Greenland and the Antarctic ice sheets came to general attention as a major evidence of climate warming and as a potential contribution to the sea-level rise, to local shortage of water resources and to other environmental risks. Here, we present a short review of the most recent data and assessments on the present status and on trends of glaciers and polar ice sheets. The Greenland ice sheet (12 % of total glacier ice volume) over the last three decades showed an increase of the extent of the surface melt area and an acceleration of many marine-terminating glaciers; as a consequence, the ice sheet is losing ice at an increasing rate that reached -263 ± 30 Gt/year in the 2005-2010 time interval, equivalent to a sea-level rise of 0.72 ± 0.08 mm/year. The much larger, higher and colder composite Antarctic ice sheet (87 % of total glacier ice volume), in the same 2005-2010 time interval, had an ice loss of -81 ± 37 Gt/year. Mountain glaciers and ice caps are retreating in all the major glacierized regions, with the exception of a few mountain areas where contrasting patterns have been observed. Although containing less than 1 % of the total glacier ice, mountain glaciers and ice caps suffered a total ice loss of -259 ± 28 Gt/year in the period 2003-2009, equivalent to a sea-level rise of 0.71 ± 0.08 mm/year. The overall contribution of glaciers and ice sheets is estimated equivalent to a sea-level rise of 1.50 ± 0.16 mm/year for the period 2003-2009, or about 60 % of the total sea-level rise in the same period. Various estimates of the total glacier contribution to the sea-level rise by the end of the twenty-first century have been recently proposed, ranging from a few decimeters to 2 m, with most plausible projections at about 0.5 m. Most probably Greenland, the Antarctic Peninsula and the West Antarctic ice sheet will continue to lose ice, while the sign of the East Antarctica contribution is uncertain. Mountain glaciers will most likely continue to lose ice, although at different rates in the various mountain regions. For the European Alps and the Southern Alps (New Zealand), a loss of more than 70 % of their present volume is expected by the end of the twenty-first century. The glaciers' contraction in the mountain areas may cause slope failures, debris mobilization, outburst floods from glacial lakes, and water deficits, particularly in the summer season, in the arid zones in the coming decades. Together with other changes occurring in the cryosphere such as the Arctic sea-ice reduction, the snow cover decline and the permafrost degradation, the glacier retreat is considered part of a larger picture of environmental changes, directly or indirectly caused or increased by the human impact, leading to new environmental conditions, thus deserving to be indicated as the Anthropocene. Still more open to future responses is the consideration if the ongoing glacier reduction and the rise of the sea level will contribute to leave such a footprint in the geologic record as to require a new stratigraphic unit, a new time epoch in the billion years long history of the Earth. © 2013 Accademia Nazionale dei Lincei

Glacial Geology and Geomorphology of Terra Nova Bay (Antarctica).

During the two first Italian Antarctic Expeditions (1985/86 and 1986/87) glacial-geological and geomorphological research has been carried out in the area of Terra Nova Bay. In particular the Cenozoic glacial sediments, the Holocene raised beaches and the Holocene glacier fluctuations have been investigated. Three main glacial drifts have been recognized. The youngest drift consists of a massive matrix-supported diamict extending up to about 350 m a.s.l. on the Northern Foothills, where it contains fragments of Pelecypods and Serpulids; it was deposited by a grounded ice-shelf during the last glaciation. In the interior mountains the upper limit of the drift rises up to about 1000 m a.s.l. The young glacial drift is characterized by frequent ice-cored topography, initial weathering stages, slightly stained granitic boulders without cavernous weathering, exept in the coastal belt. The older drift, very thin and discontinuous, occurs above the previous one, up to about 600 m on the Northern Foothills, and it is characterized by red stained granitic boulders affected by cavernous weathering. A third, oldest drift occurs up to 800 m a.s.l., composed of large and scattered boulders, strongly oxidized and affected by cavernous weathering, locally resting on a strongly developed red paleosol. At higher elevations up to about 1000 m round topped glacialy abraded reliefs, devoid of any glacial cover, can be observed and represent evidence of a still older glacial stage. Holocene beaches raised up to 30 m are well known at Terra Nova Bay (Inexpressible Island and Gerlache Inlet). In addition to the ones described by previous authors, other emerged beaches have been found in several localities on the coast of the Northern Foothills, near Evans Cove and at Edmonson Point. It is possible to distinguish two groups of emerged beaches: the first one consists of the beaches at Inexpressible Island and the Northern Foothills, ranging in altitude up to about 30 m a.s.l.; the second group, not higher than 7 m, is present at the foot of northern and eastern slopes of Mt. Melbourne. In our opinion, higher (and older) beaches are lacking in the Mt. Melbourne region because of recent volcanic activity. Several C-14 ages have been obtained from penguin remains collected in the organic horizons developed on the raised beaches; other C-14 ages were supplied by shells (Pelecypods, Barnacles and Corals) collected in marine sediments. We obtained a range for the glacio-isostatic uplift rate suggesting a value lower than 2.1 mm/yr in the last two millennia and a value lower than 4.5 but greater than 1.8 mm/yr in the four previous millennia. Evidence of Holocene glacier fluctuations have been observed close to the terminal margins of the outlet glaciers, of the ice shelves and of the local glaciers. Groups of Holocene ice-cored moraines document very small fluctuations of the ice extent of the outlet glaciers. The moraines can be differentiated on the basis of weathering degree, color of staining, development of deflation pavements, lichen cover and development of patterned ground. The Hells Gate Ice Shelf and the Nansen Ice Sheet (Shelf) advanced, during Holocene, probably because of the isostatic uplift of the coast. Near the termini of the small local glaciers at least two ice-cored moraines can be observed, showing the same differentiations mentioned above for the outlet glaciers. The moraines of the Strandline Gl. (Tethys Bay) rest on raised beaches and document two advance that were separated by a conspicuous lapse of time. They reached, respectively, a distance of more than 60 m and about 50 m from the present front. On the basis of the relationships between moraines and raised beaches, the oldest moraine has to be younger than about 5800-3800 yr B.P. and both were possibly deposited during the Late Holocene. At the foot of the eastern slope of Mt. Melbourne, near Edmonson Point, a glacier has been studied. On its south side, a complex of ice-cored moraines is to be found. It consists of a thin cover of marine sediments (laminated sands) that contains several articulated shells of Adamussium colbechi and Laternula elliptica. The fossiliferous sediments appear to have been frozen at the sole of the glacier and then entrained forward and laterally up to the surface (37 m a.s.l.), testifying to an advance of the glacier greater than 130 m that must have occured later than 600-1000 yr B.P

Glacier fluctuations in the westerna Alps during the Neoglacial as indicated by the Miage morainic amphitheatre (Mont Blanc massif, Italy)

International audienceHolocene glacier variations pre-dating the Little Ice Age are poorly known in the western Alps. Studied for two centuries, the Miage morainic amphitheatre (MMA) is composed of three subconcentric sets of c. 25 moraines. Because of its location and of a dominant mode of morainic accretion, the MMA is a well-preserved marker of the glacier dynamics during the Neoglacial. Radiocarbon dates were obtained by digging and coring in inter-morainic depressions of the MMA and through a deep core drilling in a dammed-lake infill (Combal); complementary data for the inner MMA were obtained by lichenometry and dendrochronology. Radiocarbon chronology shows that (i) the MMA not only pre-dates the Little Ice Age (LIA), but was built at least since 5029–4648 cal. yr BP (beginning of the Neoglacial); (ii) outer sets of moraines pre-date 2748–2362 cal. yr BP; (iii) the MMA dammed the Lake Combal from 4.8 to 1.5 cal. kyr BP, while lakes/ponds formed inside the moraines (e.g. from 2147–1928 to 1506–1295 cal. yr BP). The ‘Neoglacial model' proposed here considers that the MMA formed during the whole Neoglacial by a succession of glacier advances at 4.8–4.6 cal. ky BP (early Neoglacial), around 2.5 cal. ky BP (end of Göschener I), at AD 600–900 (end of Göschener II) and during the LIA, separated by raising phases of the right-lateral moraine by active dumping because of the Miage debris cover

Risultati preliminari delle ricerche geomorfologiche e glaciologiche svolte nella seconda spedizione del P.N.R.A

Glacial-geologicql observations have been carried on at Terra Nova Bay. Evidences of at least four glaciations have been observed: the oldest two are referred to the pre-Pleistocene. AI/long the coeste! belt the youngest glacial drift contains fragments of marine shells, supporting the hypothesis of the expansion of a grounded Ross Ice Shelf. Holocene glacier fluctuations have been studied and two minor neoglacial advances have been observed. Near Edmonson Point a glacier advance has been dated to about 1000 years BP . 14C ages have been obtained for Holocene raised beaches, ranging from 5770 + 60 to the present. A rate of 3 mm1year can be preliminarly estimated for the isostatic uplift during the last 4500 years. A geomorphological map at a scale 1:10.000 has been produced for the area surrounding the Italian station